1. Field of the Invention
This invention relates to a grommet, and more particularly relates to a grommet that is attached to a wire harness to be arranged in a motor vehicle and is installed in a through-hole in a vehicle body panel to protect, waterproof, and dustproof the wire harness.
2. Description of the Related Art
Heretofore, a grommet made of rubber or elastomer is attached to a wire harness to be arranged from an engine room in a motor vehicle to a passenger room. The grommet is installed in a through-hole in a vehicle body panel that partitions a vehicle body into an engine room and a passenger room to protect the wire harness passing the through-hole and to waterproof, dustproof, sound-insulate the passenger room from the engine room.
The present applicant has disclosed such a kind of grommets in JP 2007-135253 A, as shown in FIG. 8A of the present application. The grommet includes an enlarging diameter tubular section 1 provided on an outer periphery of a larger diameter side with a vehicle body latch recess 2, closing plates 3A, 3B provided on an inner periphery of the enlarging diameter tubular section 1, and a pair of half ring sections 4A, 4B provided on opposed central parts of the closing plates 3A, 3B. A smaller diameter tubular section 5 extends from a central part of a smaller diameter side of the enlarging diameter tubular section 1 to be continued to a central inner tube 5a disposed between the pair of half ring sections 4A, 4B.
As shown in FIG. 8B, after a wire harness W/H is passed through the smaller diameter tubular section 5 that protrudes toward the larger diameter side in the enlarging diameter tubular section 1, a tape T is wound around on an outer periphery of the pair of half ring sections 4A, 4B at an outer periphery side of the central inner tube 5a at a protruding side of the smaller diameter tubular section 5. The tape T is also wound around an outer periphery of the wire harness W/H drawn out from the central inner tube 5a to secure the grommet to the wire harness W/H.
In the grommet of JP 2007-135253, since the smaller diameter tubular section 5 does not protrude outward from the smaller diameter side of the enlarging diameter tubular section 1 and extends in an interior of the enlarging diameter tubular section 1, there is an advantage that can shorten the grommet.
However, in the case where the wire harness W/H has a large size in outer diameter, the smaller diameter tubular section 5 is widen in an oval figure in cross section, and the half ring sections 4A, 4B are also deformed in the oval figure in cross section with the tape T winding around an outer periphery of the half ring sections 4A, 4B. If the half ring sections 4A, 4B do not define a complete circle in cross section, as shown in FIG. 9A, closing plates 3A, 3B connected to proximal ends of the half closing rings 4A, 4B are pulled to widen a slit between opposed surfaces of the closing plates 3A, 3B to cause a clearance C and to deform a profile of the enlarging diameter tubular section 1 coupled to the semicircular closing plate sections 3A, 3B. In result, the vehicle body latch recess 2 provided on the outer periphery of the enlarging diameter tubular section 1 is also deformed into the oval figure in cross section, so that the recess 2 cannot be closely engaged with a through-hole in a vehicle body panel. Under this condition, water leakage may occur via the through-hole in the vehicle body panel.
On the other hand, in the case where the wire harness W/H has a small size in outer diameter, outer peripheries of the half closing rings 4A, 4B are compressed, with the tape T winding around the rings 4A, 4B, and the rings 4A, 4B and the tape T are deformed into an oval figure, as shown in FIG. 9B. In result, they are changed to the state shown in FIG. 9A, and the vehicle body latch recess 2 is deformed through the semicircular closing plate sections 3A, 3B. This may cause water leakage.
Further, if the half ring sections 4A, 4B and the wire harness W/H wound by the tape T are bent abruptly, as shown in FIG. 9C, the vehicle body latch recess 2 is deformed through the semicircular closing plate sections 3A, 3B. This may cause water leakage.
Further, the smaller diameter tubular section 5 extends in the enlarging diameter tubular section 1, as disclosed in JP 2007-135253. However, even if the smaller diameter tubular section 5 extends outward from the smaller diameter side of the enlarging diameter tubular section 1, the half ring sections 4A, 4B protrude from the half closing rings 3A, 3B, the half ring sections 4A, 4B cover the outer periphery of the wire harness W/H, and the tape is wound around the half ring sections 4A, 4B to secure the grommet to the wire harness W/H, the same problem described above will occur.